JP2003324300A - Method for suppressing unnecessary radio wave and road utility facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for suppressing an unnecessary radio wave which performs a radio wave absorbing function balanced between a low incident angle and a high incident angle relative to the radio wave of circular polarization in a 5.8 GHz band without impairing the transparency or appearance of a road utility facility. <P>SOLUTION: The method for suppressing the unnecessary radio wave comprises steps of: forming a radio wave absorber 5 mounted in the road utility facility and making an essential part of the road utility facility transparent to avoid the degradation of the transparency or the appearance of the facility; laminating a plurality of dielectric elements having different permittivities in a second dielectric element disposed at the radio wave coming side α of a resistance film 51 to regulate the thickness in response to the difference of the permittivities of the elements; regulating characteristics of absorbing the radio wave to the incident angle by changing the incident angle to the film 51 and the phase of the radio wave; setting a reflecting attenuation quantity at 0 to 80° of the incident angle to the absorber 5 against the radio wave of the circular polarization in the 5.8 GHz band to 20 dB or more; and providing radio wave absorbing characteristics balanced between the low incident angle and the high incident angle. Thus, the mistake of recognizing at communication or a sensing time can be further surely prevented. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of suppressing unnecessary radio waves generated during communication or sensing using radio waves, which is caused by peripheral equipment attached to a road that performs the communication or sensing, and suppresses the generation of unnecessary radio waves. Related to road incidental equipment.

[0002]

2. Description of the Related Art Originally, road traffic consists of facilities that allow safe and secure driving and the driver's compliance with rules, but as traffic volume increases and speed increases, humans can make instantaneous judgments and cope with it. It may exceed the above, and as a result, a tragic situation such as a traffic accident may occur. Especially in a zone with poor visibility such as an intersection or a sharp curve, or a zone with poor visibility, there is a situation in which a collision or a rear-end collision cannot be avoided because the invisible information cannot be grasped.

In consideration of such a situation, for example, a sensor for detecting a traveling vehicle is provided on the road side of a sharp curve point, and information detected by the sensor is provided by a roadside light emitter installed toward an oncoming vehicle in the traveling direction. Make it shine with letters and symbol markings,
There are known means by which to draw attention.

However, the means for detecting the vehicle by the above-mentioned sensor and making the oncoming vehicle recognize the roadside illuminant or the like as a medium can prevent an accident from occurring by the driver's quick judgment. There
You cannot immediately recognize information boards such as roadside light emitters,
Or delaying the treatment may lead to an accident.

On the other hand, a driving assistance road system (advanced cruise-assist) using wireless communication is used.
t Highway System) is also under development. The driving support road system is a system that provides the vehicle with information on the road such as other vehicles, pedestrians, obstacles, etc. collected from sensors installed on the road, and supports the driving. According to the system, the wireless communication between the roadside communication equipment installed on the road and the vehicle-mounted communication device mounted on the vehicle supporting the road system enables information such as invisible obstacles in front and crossing vehicles, which was impossible in the past. It is expected that it will be possible to provide the driver to the driver in real time and drastically reduce the number of accidents, aiming at dramatically safe and secure driving.

As for roads, in addition to the driving support road system, between the roadside communication equipment and the vehicle-mounted communication device for the purpose of eliminating traffic congestion at toll gates on toll roads and improving convenience by making cashless. An automatic toll collection system (Electronic Toll Collecti) that automatically pays tolls without stopping once at toll gates on toll roads by bi-directional communication
on System, hereinafter referred to as ETC. ) Has also been put to practical use. In the ETC and the driving assistance road system, the communication area is generally limited, and the short-range communication (Dedicated Short Range) is a communication method intended for a narrow range of several meters to several hundred meters.
Communication) is generally adopted.
The communication technology of the narrow area communication is expected to be applied to various fields such as parking lot management, physical distribution management, and gas station price payment, in addition to on the road.

According to the driving support road system as described above, it is possible to adopt a form in which the alarm is sounded on the vehicle side to forcibly warn the driver or the braking is automatically applied, which may lead to an accident. Will be less. However, when a radio wave is used as a communication means for communication or an attempt is made to perform sensing by the radio wave, a problem of radio wave interference occurs. For example, safety facilities attached to the road such as median strips and roadside protection fences and sound insulation walls, and road incidental equipment for the purpose of environmental protection etc. are generally made of metal, so these The transmitted radio waves are directly poured on the road surface, the equipment attached to the road or various cars and are reflected multiple times, and the radio waves are emitted in a direction different from the desired direction, so that it can be transmitted to vehicles that originally want to transmit information. Will arrive as interference radio waves, and the radio waves will be received by other vehicles as well, which may make it impossible to control the intended vehicle. That is, the received radio waves may cause interference or malfunction due to mutual interference of electromagnetic waves or delay dispersion, and it may not be possible to provide accurate information.

FIG. 1 shows a state of unnecessary radio waves generated by the reflection on the road auxiliary equipment as described above.
In the figure (a), the radio wave c from the roadside communication equipment b is emitted to the communication area d, but the road auxiliary equipment e in the communication area d
When the communication area d is expanded by the re-reflection, the information cannot be obtained at an appropriate timing, and the driver is re-reflected outside the communication area d and received by the vehicle-mounted communication device f. It can be confusing.

Further, in FIG. 2B, one roadside communication facility b
The radio wave c from No. 1 is reflected as described above, leaves the communication area d1 of this roadside communication equipment b1, reaches the communication area d2 of another roadside communication equipment b2, and reaches this communication area d2.
In the above, there is a possibility that radio waves reflected from one roadside communication facility b1 and radio waves from this roadside communication facility b2 may cause interference and deterioration of communication quality.

As described above, the generation of unnecessary radio waves due to the reflection in the road auxiliary equipment may cause a serious problem such as a malfunction of the system, or may cause the driver to be confused by receiving unclear information. In some cases, there is a problem that it may cause a serious accident related to the life of the driver.

Also in the ETC, when radio waves are reflected by peripheral road auxiliary equipment and communication failure occurs, the vehicle may pass through the toll gate without paying the charge, or the charge may be erroneous. If the gate at the toll gate is not opened, it may lead to a serious accident.

As described above, although communication using radio waves or sensing by radio waves can effectively achieve safe driving and the elimination of traffic congestion, a radio wave failure may lead to a major accident. There is a lot of potential for confusion.

Since the problem of radio wave interference is a problem caused by peripheral road auxiliary equipment when communication is performed on the road by using radio waves or when sensing is performed by the radio waves, the above-mentioned roadside equipment is Not only road-to-vehicle communication for communicating between traveling vehicles, for example, a plurality of vehicles equipped with an in-vehicle communication device, in the case of inter-vehicle communication to perform wireless communication by the in-vehicle communication device, a vehicle equipped with an in-vehicle receiving device, Even in the case of sensing performed by receiving radio waves transmitted from a transmission device built in or attached to road auxiliary equipment, there is a possibility that radio wave reflection from surrounding road auxiliary equipment may cause communication failure or sensing failure. is there.

FIG. 2 shows a vehicle equipped with an in-vehicle receiving device.
It shows a situation of unnecessary radio waves generated by reflection at the road auxiliary equipment in the case of sensing performed by receiving radio waves transmitted from a transmitting device built in or attached to the road auxiliary equipment. In order to prevent the vehicle f1 from going straight ahead without noticing the curve or colliding without noticing the presence of the oncoming vehicle f3 near a curve on a road with poor visibility, especially when visibility is obstructed due to heavy fog or snowfall. In addition, there is provided a system that radiates a radio wave d toward the vehicle-mounted receiving device of the vehicle f1 and urges the driver of the vehicle f1 to have a curve by some means. The radio wave transmitted from the transmission device b is radiated not only to the in-vehicle reception device mounted on the vehicle f1 but also to the communication area d having a certain range. The radio wave that has reached the road auxiliary equipment e formed by using a material that reflects light is reflected to become an unnecessary radio wave c, and reaches the vehicle f2 that has time to reach the curve, and the vehicle-mounted receiver of the vehicle f2. Received by vehicle f2
The warning will be given to the driver of the vehicle f2, and the driver of the vehicle f2 may confuse the traffic due to sudden braking.

The generation of the unnecessary radio wave is not limited to road traffic, but may occur outside road traffic. For example, when performing communication using radio waves or sensing by radio waves, even when performing parking lot management, logistics management, gas station price payment, etc., radio wave reflection from surrounding road auxiliary equipment may cause communication failure or sensing. There is a risk of failure, and even in such a case it becomes a problem.

Therefore, Japanese Patent Application No. 2001-1 by the present applicant
As described in No. 34785, at the time of communication or sensing using radio waves, in order to suppress unnecessary radio waves generated by peripheral road auxiliary equipment, a radio wave absorber is attached to the road auxiliary equipment, or road auxiliary equipment There is disclosed a method of forming an essential part of a radio wave absorber to absorb unnecessary radio waves and solve such a problem.

[0017]

However, the radio wave absorber mounted on the conventional road auxiliary equipment generally has a structure in which a loss material such as ferrite or carbon is mixed with a holding material such as rubber or resin. Even if the case was transparent, it was not transparent.

For example, FIG. 3 shows an ETC with multiple lanes.
However, when a vehicle 4 such as a passenger car 4C, a truck 4T, a mixer car 4M passes through, a radio wave a relating to the collection of charges from the roadside communication device 3 is transmitted to the vehicle-mounted communication device 41 mounted on the vehicle 4. Is radiated, but the radio wave a is radiated in a wide range to some extent in order to ensure reception at the vehicle-mounted communication device 41. Radio waves radiated to other than the in-vehicle communication device 41 become unnecessary radio waves a1, but a part of them is relatively high in vehicle height,
When hitting the mixer section 4M1 or the like of the mixer truck 4M whose upper surface has a curved surface made of metal, the hit radio wave is reflected laterally or obliquely downward, and an unnecessary radio wave a2 is generated. Vehicles 4C in which such unnecessary radio waves a1 and a2 travel in other lanes in the same direction, or vehicles 4C, 4T travel in lanes in the opposite direction.
May be received by the vehicle-mounted communication device 41, and the charge may be erroneously collected.

In order to prevent the propagation of unnecessary radio waves to other lanes, it is necessary to suppress the propagation of unnecessary radio waves by providing a lane partition wall or a central line partition wall made of a radio wave absorber having no transparency on the lane. In order to suppress unnecessary radio waves from the cargo bed of a truck with a relatively high vehicle height as described above, it is necessary to provide a wall with a height of 5 to 6 m, and even more than in a toll booth with a narrow lane, This will increase the driver's feeling of oppression and anxiety. In addition, the number of lanes at a tollgate is generally greater than the number of lanes to travel, and if a conventional electromagnetic wave absorber is installed between lanes, the view is blocked and the vehicle traveling in an adjacent lane becomes invisible, resulting in merging. The risk of vehicles contacting each other increases.

FIG. 4 shows an example of the flow of radio waves communicated between roadside vehicles in a roadside vehicle communication zone for AHS on a viaduct. A sound insulation wall 21 extends along the outer wall 11 of the elevated road 1,
In a general road form in which a guard fence 22 is provided in the roadside, a set of roadside communication equipment for AHS such as the roadside communication equipment 3 is installed scattered at key points on the roadside.
It forms a road-to-vehicle communication zone for the purpose of HS. In the road-to-vehicle communication zone for such AHS, when the vehicle 4 equipped with the on-vehicle communication device 41 for AHS enters, communication is performed with the roadside communication equipment 3,
It provides necessary information to the vehicles 4 existing in this zone.

At that time, of the radio waves a radiated from the roadside communication equipment 3, the unnecessary radio wave a1 which is directly injected into the sound insulation wall 21 or the protective fence 22 is reflected by the metal surface of the sound insulation wall 21 or the protective fence 22, The indirect unnecessary radio wave a2 is received by the vehicle-mounted communication device 41 of the vehicle 4, and further, the indirect unnecessary radio wave a3 is generated by repeating complicated multiple reflections even on the road surface or road auxiliary equipment. Therefore, there is a possibility that radio waves a received by the vehicle-mounted communication device 41 of the vehicle 4 directly from the roadside communication equipment 3 may interfere with the radio wave a or the communication quality may deteriorate.

In this figure, a vehicle 4 traveling in the opposite lane
H, unnecessary radio wave a1 to the vehicle 4K traveling under the viaduct,
Although the suppression of the propagation of a2 and a3 can be prevented by attaching a conventional electromagnetic wave absorber to the sound insulation wall 21 or the protective fence 22,
It is important to make the driver visually recognize the visual information and the scenery on the other side of the median strip 12, and it is necessary to secure a field of view because it is installed as a partition wall of the joint flow path, In a place where a problem exists, if a conventional electromagnetic wave absorber is attached, the field of view and light rays are blocked,
It is difficult to attach a radio wave absorber, and a conventional sound insulation wall made of a resin plate or glass can secure a field of view and a light beam, but transmits a radio wave, so that an unnecessary radio wave cannot be suppressed.

When a radio wave absorber having no conventional transparency is attached to the outer surface of the existing road auxiliary equipment,
The colors and shapes of equipment attached to the road will be hidden,
Further, there is a problem in that it cannot be installed at a location that impairs the function of the road auxiliary equipment, for example, at the marking surface of the signboard. Furthermore, since the electromagnetic wave absorber is generally black, when it is attached to equipment attached to a road, it often impairs the landscape, especially in urban areas.

Therefore, the present invention provides a peripheral road auxiliary equipment for performing communication or sensing at the time of communication or sensing using radio waves even when installed or installed as road auxiliary equipment without obstructing the surrounding field of vision or light rays. The present invention provides a method for suppressing unnecessary radio waves generated due to the above, and road incidental equipment capable of suppressing the generation of unnecessary radio waves.

[0025]

In order to achieve the above object, the present invention has the following constitution. That is, at the time of communication or sensing using radio waves, in order to suppress unnecessary radio waves generated by peripheral road auxiliary equipment, a transparent radio wave absorber is attached to the road auxiliary equipment,
Alternatively, the main part of the road auxiliary equipment is formed of a transparent electromagnetic wave absorber, and the transparent electromagnetic wave absorber has a transparent resistance film arranged in the direction of arrival of electromagnetic waves, and the back surface thereof has a thickness of about λg / 4 (where λg is A transparent first dielectric material (representing the wavelength of radio waves in the dielectric body) is arranged, a radio wave reflector that transmits light is further arranged on the back surface of the dielectric body, and a transparent electric wave arrival side of the resistive film is further arranged. A second dielectric is arranged, the plurality of dielectrics having different permittivities are laminated, and the incident angle of the circularly polarized radio wave in the 5.8 GHz band with respect to the radio wave absorber. Is 0
It is characterized in that the return loss is 20 dB or more in the range of 80 to 80 degrees.

According to the unnecessary radio wave suppression method of the present invention,
By attaching transparent radio wave absorbers to road incidental equipment, or forming the main parts of these road incidental equipment from transparent radio wave absorbers, by preventing unnecessary reflection and transmission of radio waves,
The function of each installed purpose is demonstrated, and since the electromagnetic wave absorber is transparent, it suppresses unnecessary radio waves during communication or sensing using radio waves without blocking the field of view or light rays. It can be effectively achieved.

Further, in the transparent electromagnetic wave absorber, the second dielectric is formed by laminating a plurality of dielectrics having different dielectric constants, so that the thickness is adjusted according to the difference in the dielectric constants of the dielectrics.
By changing the incident angle to the resistive film and the phase of the radio wave, the characteristics of radio wave absorption with respect to the incident angle can be adjusted to 5.8G.
For circularly polarized radio waves in the Hz band, the return loss is 2 when the angle of incidence on the radio wave absorber is 0 to 80 degrees.
It is set to 0 dB or more and is provided with a well-balanced electromagnetic wave absorption characteristic from a low incident angle to a high incident angle, and it is possible to more reliably prevent misidentification during communication or sensing. The second dielectric includes a second first dielectric arranged on the radio wave arrival side of the resistance film and a second second dielectric arranged on the radio wave arrival side of the second first dielectric. The second second dielectric is composed of at least two dielectrics, and the second dielectric has a higher dielectric constant than the second first dielectric, so that the characteristic of the radio wave absorption with respect to the incident angle can be easily adjusted. Further, the second first dielectric may consist of air.

The above resistance film is preferably a transparent film formed by ion plating, vapor deposition, sputtering, coating or the like of a metal, a metal oxide, a metal nitride or a mixture thereof, and the above metal or metal. The oxide or metal nitride is preferably at least one selected from the group consisting of silver, ITO (indium oxide / tin oxide), tin oxide, zinc oxide, and titanium nitride. Further, the transparent dielectric may be at least one selected from the group consisting of air, glass and transparent organic polymers, and the radio wave reflector may be a metal wire grating and / or a transparent metal. It is preferably a thin film, and the transparent metal thin film is preferably a transparent film prepared by ion plating, vapor deposition, sputtering, coating or the like of a metal, a metal oxide, a metal nitride or a mixture thereof. Further, the metal, metal oxide, and metal nitride are silver,
It is preferably at least one selected from the group consisting of ITO (indium oxide / tin oxide), tin oxide, zinc oxide, and titanium nitride.

When the radio wave absorber is attached to the road auxiliary equipment, it is effective to attach it along at least the radio wave arrival side of the road auxiliary equipment.

In the transparent wave absorber, it is preferable that at least one of the constituent layers is adhered using a transparent adhesive synthetic resin, and the transparent adhesive synthetic resin is EVA (ethylene vinyl acetate). Copolymer), PVB
At least one selected from the group consisting of cross-linked type such as (polyvinyl butyral), modified polyethylene, modified resin of modified polypropylene, epoxy-based and urethane-based adhesives may be used.

In the present invention, the communication using radio waves may be road-vehicle communication in which roadside communication equipment installed on a road and vehicle-mounted communication device mounted in a vehicle wirelessly communicate, or vehicle-mounted communication device. A plurality of vehicles equipped with may be inter-vehicle communication in which wireless communication is performed by the in-vehicle communication device.

The sensing using radio waves may be performed by a vehicle equipped with an in-vehicle receiving device receiving radio waves transmitted from a transmitting device built in or attached to road auxiliary equipment.

The communication using the radio waves may be communication performed in the driving support road system, narrow area communication, or narrow area communication in the driving support road system. . The driving assistance road system (Advanced Cruise-Assist H
IGHWAY SYSTEM, hereinafter referred to as AHS. ) Is a system that provides the vehicle with information on the road such as other vehicles, pedestrians, obstacles, etc., collected from sensors installed on the road, and supports traveling.
d Short Range Communicati
on, hereinafter referred to as DSRC. ) Means AHS or ET
It is a communication method for a narrow range of several meters to several hundred meters that is generally adopted in C and the like.

Further, since unnecessary radio waves are generated by reflection and transmission of road auxiliary equipment in AHS or the like, the radio wave absorber is an unnecessary radio wave generated by reflection and transmission of peripheral road auxiliary equipment. It is preferable that the electric wave absorber is A
DSRC generally used in HS, ETC, etc.
It may be one that suppresses reflection and transmission of the general frequency of 5.8 GHz band.

Further, it is preferable that the transparent electromagnetic wave absorber has a coating for preventing water droplets from adhering to the outer surface thereof. The electromagnetic wave absorber has a radio wave absorption property that is reduced due to the irregular reflection of radio waves near the surface by water droplets that adhere to its outer surface, but this can be prevented or mitigated by applying a water droplet adhesion prevention coating to the outer surface. At the same time, the resistance layer and the reflection layer can be protected. The coating is
It may be applied directly to the surfaces of the resistance layer and the reflection layer, or a synthetic resin having transparency such as polycarbonate or acrylic resin or a transparent dielectric such as glass may be disposed on the front surface of the resistance layer and the reflection layer. , May be applied to its outer surface.

As a coating for preventing water droplets from adhering, it is preferable to provide a superhydrophobic coating layer or a superhydrophilic coating layer on the outer surface of the radio wave absorber, and a snow glaze coating layer may be provided. By providing the superhydrophobic coating layer, the water droplets attached to the outer surface are spherical and easily slipped off due to their own weight. By providing the superhydrophilic coating layer, the water adhering to the outer surface does not become water drops but becomes a uniform water film on the surface, and diffuse reflection of radio waves is suppressed. Further, by providing the snow-and-ice cover layer, the water repellency allows the water droplets adhering to the outer surface to be slid off by its own weight, and even if the snow and ice adhere to the outer surface, it can be easily slid off.

The super water-repellent coating layer can be formed by applying a water repellent agent to the surface of a shape suitable for water repellency. The superhydrophilic coating layer is a coating layer containing a photocatalyst such as titanium oxide, and is activated by irradiation with ultraviolet rays,
In addition to exhibiting superhydrophilicity, contaminants attached to the outer surface can be decomposed to have a function of preventing stains. The electromagnetic wave absorber according to the present invention is transparent, and by providing a function of preventing stains, it can be effective in maintaining its see-through property.

The snow glacial coating layer is the coating layer described in Japanese Patent Application No. 2001-103031 by the present applicant,
The surface tension of the outer surface is 35 dyne / cm or less, the water repellency and the sliding angle of water droplets are 40 degrees or less, and the attached snow and ice can be easily slid off. As with the adhesion of water drops, the adhesion of snow and ice is a factor that causes deterioration of the radio wave absorption characteristics. Therefore, by providing such a coating layer on the outer surface, the prevention or mitigation thereof can be achieved.

Further, in the present invention, a main component is at least one material selected from the group consisting of transparent materials such as transparent polycarbonate resin, acrylic resin, polyacrylonitrile resin, polyvinyl chloride resin and glass. It is suitable to apply to road incidental equipment.

The road incidental equipment applied to the present invention is installed mainly for the purpose of safety facilities attached to roads and environmental protection, and is a source of unnecessary radio waves due to its reflection and transmission. It is applied to various road incidental equipment without particular limitation.

For example, as a road accessory, there is a soundproof wall installed along the side edge of the road or the median strip. The soundproof wall includes various soundproof walls corresponding to the purpose of installation, such as a soundproof wall having a see-through property using a light-transmitting synthetic resin or a light-transmitting plate such as glass.

As other road auxiliary equipment, a tunnel interior plate installed on the wall surface or ceiling surface of the tunnel to improve the visual environment in the tunnel, and attached to the backside of the girder of the viaduct or bridge to improve the view of the backside of the girder. Girder back face decorative plate, viaduct leg decorative plate for improving the scenery of viaducts and bridge legs, road signs for transmitting information to the driver, and other features such as wall railings, guardrails, fences for safe driving and protecting the vehicle , Line of sight indicators, point markers, emergency telephones, roofs of toll gates, traffic lights, pedestrian bridges, etc.

These road incidental equipments are effective for reducing noise of vehicles and sound insulation, improving visual environment and scenery, and promoting safe driving of vehicles. Although it has a function, when a radio wave hits these, the radio wave is reflected and transmitted, and unnecessary radio waves are generated around it.Therefore, attach a transparent wave absorber to these road incidental equipment. Or, by forming the main part of these road auxiliary equipment from a transparent electromagnetic wave absorber to prevent unnecessary reflection and transmission of electromagnetic waves, the function according to each installed purpose can be achieved and Since the absorber is transparent, it is possible to effectively suppress unnecessary radio waves at the time of communication using radio waves or sensing without blocking the visual field and light rays.

In addition to the above, as a road auxiliary equipment applied to the present invention, it is particularly preferably used that it is installed between a plurality of lanes to prevent unnecessary transmission and reflection of radio waves between the lanes. There are partition walls and lightings installed on the edge of the lane where the car can move. Since these can prevent transmission and reflection of radio waves without blocking the field of view and light rays, extremely great effects can be obtained, such as reducing the feeling of pressure and blockage to the driver and maintaining the lighting effect.

Next, the road incidental equipment according to the present invention is provided with a radio wave absorber for suppressing unnecessary reflection and transmission of radio waves at the time of communication or sensing using radio waves,
Or a road auxiliary equipment whose main part is a radio wave absorber, and said road auxiliary equipment is a soundproof wall, tunnel interior board, girder back decorative board, viaduct leg decorative board, road sign, wall balustrade, tollgate roof, Toll gate windows, guardrails, fences, line-of-sight guides,
At least one selected from the group consisting of a point marker, an emergency telephone, a traffic signal, a pedestrian bridge, a partition wall installed at the edge of a lane having a communication area, and an illumination lamp.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 5 is an explanatory diagram showing an example of the flow of radio waves that are bidirectionally communicated between roadside vehicles in a roadside vehicle communication zone for AHS to which the embodiment of the present invention is applied. In a road form in which a general road auxiliary equipment is formed such that a sound insulation wall 21 is extended along the outer wall 11 of the road 1 and a protective fence 22 is provided in the median strip 12, the AHS such as the roadside communication equipment 3 is provided. A set of targeted roadside communication equipment is installed scatteredly at key points on the roadside to form a roadside-vehicle communication zone intended for AHS. In the road-vehicle communication zone for such AHS, the vehicle 4 equipped with the on-vehicle communication device 41 for AHS
When the vehicle enters, communication is performed with the roadside communication equipment 3, and information necessary for the vehicle 4 existing in this zone, such as vehicle authentication information, security information, vehicle sensing information, road surface condition, Infrastructure sensing information such as the existence of obstacles and road-related information will be provided to the driver in real time, so that it will be possible to receive collision prevention services against obstacles, lane departure prevention, safe inter-vehicle distance maintenance services, etc. Therefore, measures are taken to prevent accidents at dangerous places.

However, if the above-mentioned communication is carried out in a road-to-vehicle communication zone for the purpose of AHS in a state where unnecessary radio wave reflection is not suppressed, among the radio waves a radiated from the roadside communication equipment 3, the sound insulation wall 21 and the protective wall 21 are directly protected. The radio wave a1 that is poured into the road auxiliary equipment such as the fence 22 is reflected by the metal surface of the road auxiliary equipment, is also reflected by the road surface, etc., and becomes an indirect radio wave a2 by repeating complex multiple reflections. In-vehicle communication device 41
Therefore, there is a possibility that the radio wave a received by the vehicle-mounted communication device 41 of the vehicle 4 directly from the roadside communication equipment 3 may interfere with the radio wave a or the communication quality may deteriorate. Further, when the sound insulation wall 21 is formed by using polycarbonate, glass, or the like as a main part, the unnecessary radio wave a1 may affect the vehicle 4K running under the elevated structure. Therefore, when the radio wave absorber 5 is attached to the radio wave reflecting surface or the radio wave transmitting surface of the road incidental equipment such as the sound insulation wall 21 and the protective fence 22, or the road incidental equipment 2 is formed by the radio wave absorber 5, the roadside communication is performed. Since the radio wave a1 radiated from the equipment 3 is suppressed from being reflected and transmitted by the radio wave absorber 5, unnecessary radio waves are suppressed and radio waves received by the vehicle-mounted communication device 41 of the vehicle 4 are not interfered with or deteriorated in communication quality. .

The radio wave absorber 5 is provided with a resistance layer having a large surface resistance value on the radio wave arrival side of a dielectric resin such as a transparent resin such as polycarbonate or acrylic resin or glass, and on the opposite side. A reflection layer having a small surface resistance value that can function as a radio wave reflection layer is provided. The resistive layer is a transparent layer made of a resistive film or a resistive wire array made of a metal oxide or a metal nitride, and the reflective layer is a transparent layer made of a metal wire grating or a metal thin film. . It is formed by using a conductor such as a resistance wire or resistance film, and a conductive radio wave absorber that attenuates the radio wave by the conductive current that flows in the conductor when it is irradiated with radio waves. By using the resistance wire or the resistance film having the above, it is possible to provide the conductor without impairing the transparency.

Further, in order to prevent or alleviate the deterioration of radio wave absorption characteristics due to the adhesion of water droplets and protect the resistance layer and the reflection layer, the surfaces of the resistance layer and the reflection layer are provided with super water repellency and super hydrophilicity. Is preferred. Further, in order to hold and protect the resistance layer and the reflection layer, a transparent resin such as synthetic resin having transparency such as polycarbonate or acrylic resin, or a transparent dielectric such as glass may be present. In order to prevent or alleviate the deterioration of radio wave absorption characteristics, it is preferable that the surface of the dielectric is provided with superhydrophobicity or superhydrophilicity.

FIG. 6 is a sectional view showing the configuration of the radio wave absorber in detail and showing one form of the configuration of the radio wave absorber. For example, the second dielectric 53, the resistance layer 51, the first dielectric 54 that is a transparent resin plate, the reflective layer 52, and the back surface protection portion 55 that is a transparent resin plate are laminated in this order from the radio wave arrival direction α. It is what 45 degrees to 8
In order to exhibit high absorption performance for radio waves incident at an angle of 0 degree, a plurality of types of dielectrics having different dielectric constants are used. That is, the second dielectric body 53 is formed by stacking a plurality of dielectric bodies 531, 532, and 533 having different permittivities, and the thickness of the second dielectric body 53 is adjusted based on the difference in the respective permittivity to arrive at the electric wave of the resistance layer 51. Side α
In this case, the incident angle to the resistance layer 51 and the phase of the radio wave are changed to adjust the characteristic of the radio wave absorption with respect to the incident angle.

It is preferable that the radio wave absorber 5 which is the laminated body is provided with an adhesive layer between the respective layers to maintain the shape and thickness, and the adhesive layer is not particularly limited as long as it has transparency. Alternatively, a urethane-based or epoxy-based adhesive, a modified polyethylene, a modified polypropylene, or a cross-linkable resin such as EVA or PVB may be used. Among these, EVA, which has excellent weather resistance and is easily heat-processed, can be preferably used.

By providing an adhesive layer between the respective layers to maintain the shape, it is possible to prevent moisture from entering between the layers and prevent deterioration of radio wave characteristics due to this moisture. In addition, the thickness of a generally commercially available polycarbonate plate or the like is 1, 2, 3, 5, 8 mm or the like, and when a generally commercially available polycarbonate plate or the like is directly laminated to form a radio wave absorber, the thickness is Since the range of adjustment of is limited, it is difficult to obtain the electromagnetic wave absorption performance to be set. It is possible to polish or melt-compress to adjust the thickness of a generally commercially available polycarbonate plate or the like, but when polished, the transparency of the resin plate is impaired,
In the case of melt compression, there are problems that the crystal structure of the resin changes and the dielectric constant varies, and that the steps related to melt compression require labor and cost.

Even when a commercially available polycarbonate plate or the like is used, by using the adhesive layer, the second dielectric 53 and the first dielectric 54 can be adjusted to desired thicknesses to absorb radio waves. Performance can be easily set.
Furthermore, when a cross-linkable resin such as EVA is used, the thickness after compression can be set in advance in thermocompression molding and the thickness can be adjusted strictly, so that the electromagnetic wave absorption performance is reduced due to the thickness error of the polycarbonate plate or the like. It is possible to reduce. Further, in designing the radio wave absorption performance, it is possible to design in consideration of the adhesive layer in advance.

The transparent resin plate, which is the first dielectric 54, is a dielectric and transmits radio waves. The resistance layer 51 is a resistance film made of a PET film or the like on which a metal oxide is attached, and the reflection layer 52 is a radio wave reflector made of a PET film or the like on which a metal wire grating is attached. The radio wave incident from the direction of arrival of the radio wave is transmitted while being refracted by the second dielectric, is attenuated by the resistance layer 51, and the radio wave passing through the resistance layer 51 is further transmitted through the first dielectric 54 and is reflected by the reflection layer. The light is reflected by 52, passes through the first dielectric 54 again, and is attenuated by the resistance layer 51.

By changing the thickness of the resistance layer 51 and the first dielectric 54 and the material of the first dielectric 54 according to the wavelength of the radio wave that needs to be suppressed, the reflection attenuation efficiency of the radio wave is further improved. It is possible to For example, when the wavelength of the radio wave is λg in the dielectric, the thickness of the absorption film and the first dielectric is set to about λg / 4, and the radio wave traveling direction is expected from the surface of the dielectric 531 on the radio wave arrival side. By matching the radio wave impedance with the impedance of free space, unnecessary radio waves are attenuated more efficiently. In addition, the absorption characteristics of the radio wave absorber can be set by using the first dielectric 54 such as various transparent synthetic resins, glass, air, etc. according to the application.

Of the plurality of dielectrics 531, 532, 533 forming the second dielectric 53, one functions as a second dielectric having a small dielectric constant arranged on the radio wave arrival side of the resistance film. However, the other one is not particularly limited as long as it functions as the second second dielectric having a higher dielectric constant arranged on the radio wave arrival side than the second first dielectric. The second dielectric having a small dielectric constant may be air, and it is preferable to use the intermediate dielectric 532 as an air layer in order to maintain the thickness of the air layer and protect the resistance film. . As for the dielectric other than the air layer, transparent synthetic resin, glass, or the like may be appropriately used according to the characteristics of radio wave absorption. Also, the thickness of each may be adjusted as appropriate according to the characteristics of radio wave absorption.

Further, as shown in FIG. 7, the radio wave absorber 5 has a first dielectric 54, a resistance layer 51, and a second dielectric 53 which are laminated on both sides of the reflective layer 52 in this order. It may be a radio wave absorber 5a capable of absorbing radio waves from both the radio wave arrival directions α and β. For example, in a partition wall provided between lanes, both lanes may serve as a road-vehicle communication zone, and radio waves may arrive from both lanes. In such a place, the electromagnetic wave absorbers 5 that absorb the electromagnetic waves from one side shown in FIG. 6 may be arranged back to back, but by using the electromagnetic wave absorber 5a, only one electromagnetic wave absorber is used for both. It is possible to suppress unnecessary radio waves coming from.

The electromagnetic wave absorber 5 formed in this way
When used for the sound insulation wall 21, as shown in FIG. 8, for example, the transparent radio wave absorber 5 is used as a translucent plate, and a frame body made of metal such as aluminum around the transparent radio wave absorber 5 is held. The transparent sound insulating panel 21 is held by 211, and a plurality of these are used to stack a plurality of layers in the vertical direction to form a sound insulating wall. A sheet-shaped radio wave absorber 5 is preferably attached to the surface of the frame body, and the radio wave absorber 5 attached to the frame body can be applied regardless of whether or not it is transparent. Transparent wave absorber 5 and frame 2
The radio waves that have reached 11 are attenuated by the respective radio wave absorbers 5 and their reflection and transmission are suppressed. If water droplets are attached to the transparent radio wave absorber 5 to form a water film, radio waves are easily reflected by the water film. Therefore, the surface of the transparent radio wave absorber 5 is super water repellent by a water repellent, It is preferable that a photocatalyst such as titanium oxide is provided with superhydrophilicity and snow gliding properties to suppress the attachment of water drops and snow and ice.

Further, the sound insulation wall 21 may be as shown in FIG. The transparent sound-insulating wall 21a has a transparent wave absorber 5 arranged on the front surface and a frame body 21a1 made of metal such as aluminum for supporting the transparent wave absorber 5 mounted on the back side. By disposing the transparent electromagnetic wave absorber 5 on the front surface, the electromagnetic wave absorbing function is provided and it is not necessary to attach the electromagnetic wave absorber to the metal frame body 21a1 which is the electromagnetic wave reflector.

FIG. 10 is a sectional view of the sound insulation wall shown in FIG. The radio wave absorber 5 which is the translucent plate 21a is fixed to the frame body 21a1 by bolts 6, but the bolts are slidable within the frame body 21a1 for convenience of attachment. The bolt 6 is preferably made of a material that is not a radio wave reflector, and is preferably made of synthetic resin or the like. In addition, such as metal,
When a bolt formed of a material that reflects radio waves is used, it is preferable to attach a radio wave absorber to the radio wave incoming side of the bolt 6.

Further, the sound insulation wall 21 may be as shown in FIG. The transparent sound insulation wall 21b is a frame member 21b.
1, the transparent electromagnetic wave absorber 5 is inserted into the opening groove opened above 1, and the transparent electromagnetic wave absorber 5 is fixed to the frame member 21b1.
It is fixed by 1b2. Such sound insulation wall 21b
Since the frame is not formed around the entire transparent electromagnetic wave absorber 5, the appearance is good, and the view is obstructed by the frame when the driver views the external scenery. Can be reduced.

As described above, the radio wave absorber 5 is attached over the entire surface of at least the radio wave incident side of the road incidental equipment such as the sound insulating wall 21 and the protective fence 22, and the radio wave a1 coming into the surface of the radio wave absorber 5 is Almost no reflection or transmission by the radio wave absorber 5, and disappears or becomes weak. Therefore, the radio wave a received by the vehicle 4 equipped with the in-vehicle communication device 41 for AHS mainly obtains only the straight traveling radio wave from the roadside communication equipment 3, and there is no interference or deterioration in communication quality, and thus unnecessary radio waves. Is suppressed.

In the present invention, as a road auxiliary equipment for suppressing the generation of unnecessary radio waves, side edges and central separation of a road such as a sound-insulating wall having a see-through property using a light-transmitting plate made of a light-transmitting synthetic resin or glass. A soundproof wall installed along the strip, a tunnel interior plate installed on the wall or ceiling of the tunnel to improve the visual environment inside the tunnel, and a girder installed on the back of the girders of viaducts and bridges to improve the view of the back of the girder Back surface decorative plate, viaduct leg decorative plate for improving the scenery of viaducts and bridge legs, partition walls installed between lanes of roads where vehicles travel in the same or opposite directions, roads that convey information to the driver Signs, other, safe driving of vehicles and protecting vehicles, wall balustrades, guardrails, fences, line of sight indicators, lighting, point markers, emergency telephones,
Toll booths, traffic lights, pedestrian bridges, etc. can be exemplified.

In order to provide these road auxiliary equipment with the radio wave absorbing performance by the radio wave absorber 5, appropriate means or wave absorbers 5 are applied according to the type of road auxiliary equipment.
For example, in the above-mentioned form, the transparent plate itself, which is a part of the road auxiliary equipment, is the radio wave absorber 5, but these radio wave absorbers 5 are formed into a sheet shape or a film shape, and are attached to the outer surface of the road auxiliary equipment. Alternatively, when the radio wave absorption performance is designed including the road auxiliary equipment formed of synthetic resin or the like existing on the radio wave arrival side of the radio wave absorber 5,
The radio wave absorber 5 may be arranged inside the road auxiliary equipment. Further, the road auxiliary equipment itself may be formed by the radio wave absorber 5.

FIG. 12 shows an installation condition near the toll booth 8 having a roof 81 supported by the pillars 82 of the partition wall 2A installed between the lanes in which road auxiliary equipment runs in the same direction. 1 shows an embodiment in which a partition wall 2A is provided with a radio wave absorption performance. The vehicle enters in the direction of γ, and the roadside communication facility 3 emits the radio wave a toward the vehicle to emit a radio wave related to toll collection, but when the emitted radio wave hits the entering vehicle, it is regarded as an unnecessary radio wave in the vehicle in the adjacent lane. Propagated. A partition wall 2A between lanes whose main part is a transparent wave absorber 5 is fixed by using columns 31 and beams 32, and is installed between the lanes to block the left and right fields of view of a passing vehicle. Therefore, unnecessary radio waves can be suppressed.

Since the partition wall 2A forms a gate-shaped rigid frame structure with the columns 31 and the beams 32, it is possible to secure the installation strength of the partition wall 2A against a wind load with a smaller foundation. The column 31 and the beam 32 are attached with an electromagnetic wave absorber or are formed of an electromagnetic wave absorber. Further, in the present embodiment, the partition wall 2A is provided not only on the island 7 near the approach lane to the tollgate but also inside the tollgate 8 to more reliably suppress unnecessary radio waves.

As described above, what is regarded as a problem as an unnecessary radio wave is that reflected from the bed of the truck, and the lane partition 2A requires a ground clearance higher than that height. The height is preferably 5 to 6 m. At the lower end, since the incident angle of the radio wave from the roadside communication device 3 is small and the reflected radio wave cannot reach the angle received by the vehicle-mounted device from below, the height is 1 to 2 m from the road surface. It may even have a gap. By providing such a gap, the wind load can be reduced.

FIG. 13 shows an embodiment according to the present invention and is a perspective view from below near the toll booth. When the road auxiliary equipment is a toll road toll gate with an ETC-equipped gate, the roadside communication equipment 3
This is a portion where the radio wave a emitted from the vehicle may be reflected by hitting a road surface or a traveling vehicle and hindering the collection of charges. In the embodiment shown in this figure, the island 7 is also used.
It is preferable to provide a partition wall 2A made of a transparent electromagnetic wave absorber 5 on the top. The toll booth 8 is constructed and the roof 81 of the toll booth
For the pillar 82, the island 7, and the gate 33 of the ETC, a radio wave absorber having no transparency can be used.

However, the cover 2B of the illumination lamp attached to the roof of the tollgate is a portion where it is necessary to allow light rays to pass therethrough. It is possible to prevent unnecessary transmission of radio waves and reflection from the inside of the cover 2B of the illumination lamp. Similarly, the window 2C of the toll booth is also a portion that requires transparency, and by using the transparent electromagnetic wave absorber 5 according to the present invention in such a portion, it is possible to provide electromagnetic wave absorption performance without blocking the field of view and light rays. Can be made.

FIG. 14 shows a case where the road auxiliary equipment is a road sign 2D for transmitting road-related information to the driver, and the marking surface 2D1 of this road sign 2D is provided with an electromagnetic wave absorbing performance. It shows one form, marking surface 2
D1 is usually formed of a metal such as aluminum, which is a radio wave reflector, and has a large surface area and is slightly inclined toward the road surface so that the driver can easily recognize the information. It is easily reflected. If the marking surface 2D1 is provided with a radio wave absorber having no transparency and radio wave absorbing performance is provided, information cannot be transmitted to the driver, so that the front surface of the marking surface 2D1 can be transparent. By disposing the radio wave absorber 5, radio wave absorption performance can be provided without impairing the function as the road sign 2D. In addition, the pillar 2D2 and the cross beam 2
It is preferable to attach a radio wave absorber also to D3, and this radio wave absorber can be applied regardless of whether or not it has transparency.

FIG. 15 shows a case where the road auxiliary equipment is a tunnel interior plate 2E which is installed on the wall surface or ceiling surface of the tunnel to improve the visual environment inside the tunnel. 1 shows an embodiment in which a radio wave absorber made of a synthetic resin for improving the visual environment, a tile, a coated metal plate, or the like, is transparent to the tunnel interior plate 2E attached to the wall surface of the tunnel 2E2. 5 shows a state in which 5 is attached. By such a method, it is possible to easily provide a radio wave absorbing function to the road auxiliary equipment already installed without changing its appearance. Further, the transparent radio wave absorber 5 may be applied to the cover 2Ba of the illumination lamp in the tunnel.

FIG. 16 shows a case where the road auxiliary equipment is a girder back face decorative plate 2F which is attached to the back face of the girder 2F1 of the viaduct or the bridge to improve the view of the back face of the girder. 1 shows an embodiment having absorption performance, for example, a girder back face decorative plate 2 made of synthetic resin, tile, coated metal plate or the like and attached to the girder back face 2
By mounting the transparent electromagnetic wave absorber 5 on the front surface of F, it is possible to easily provide an electromagnetic wave absorbing function to an already installed girder back surface decorative plate without changing its appearance.

In the case of the viaduct leg decorative plate for improving the scenery of the viaduct or the leg portion of the bridge, a radio wave absorber is provided by attaching the radio wave absorber to the front surface in substantially the same manner as in the case of the girder back decorative plate. Can be made.

FIG. 17 shows a case where the road auxiliary equipment is a wall height section 2G for preventing the safe running of the vehicle and the vehicle protruding to the outside of the road or to the oncoming lane. 1 shows an embodiment of the
A sheet-shaped radio wave absorber 5 is attached to a surface 2G1 of a concrete wall balustrade 2G by using anchor bolts, an adhesive material, or a combination thereof.

FIG. 18 shows a case where the road auxiliary equipment is a protective fence, which is a guardrail 2H in the present embodiment, and shows an embodiment in which the guardrail 2H is provided with an electromagnetic wave absorbing performance. A sheet-shaped radio wave absorber 5 having an uneven surface is attached to the surface of the guardrail 2H by using a bolt, an adhesive material, or a combination thereof so as to suppress light reflection. By forming the radio wave absorber 5 into a sheet shape, it can be easily attached along the surface of the guardrail 2H and can be retrofitted to the existing guardrail 2H without changing its appearance.

FIG. 19 shows an embodiment in which the road auxiliary equipment is an overbridge type electric road marking device 2J, and the road marking device 2J is provided with a radio wave absorbing performance. The road sign device 2J
A sheet-shaped or plate-shaped electromagnetic wave absorber 5 is provided on the lower surface of the.

In addition, as road-related equipment, a line-of-sight guide for guiding a vehicle, a road lighting for illuminating the road, a point mark for displaying a distance from a reference point installed at a predetermined distance, an emergency telephone, etc. for a highway, etc. There are traffic lights and pedestrian bridges around the intersection.
Almost in the same manner as described above, it is possible to provide the electromagnetic wave absorption performance and suppress the generation of unnecessary radio waves.

Although various examples of providing the road incidental equipment with the electromagnetic wave absorbing performance have been described above, the electromagnetic wave absorber 5 as described above has the back surface protection portion 55, and the electromagnetic wave absorber 5 is provided on the second dielectric 53. Since the function of protection can be added, the electromagnetic wave absorption performance can be maintained for a long time. Further, by providing a super water-repellent coating layer or a snow glaze coating layer on the surface of the back surface protecting portion 55 or the second dielectric 53, it is possible to provide snow resistance, or a super hydrophilic coating layer using a photocatalyst or the like. By providing
It may be provided with the ability to reflect radio waves due to water droplets and to easily clean contaminants.

[0079]

EXAMPLES Examples of radio wave absorption characteristics of the present invention will be specifically described below.

(Embodiment) FIG. 20 is a sectional view showing the structure of a radio wave absorber according to a second embodiment of the present invention.
Film F made of (polyethylene terephthalate)
A metal oxide-deposited resistance layer 51, a metal-deposited reflection layer 52, and a polycarbonate plate P as a dielectric.
And an air layer G are laminated as shown in this figure.
The polycarbonate plate P and the air layer G are dielectrics having different dielectric constants. The thickness of each layer is d1 = 1, d
2 = 0.188, d3 = 8.2, d4 = 0.188, d
5 = 1, d6 = 3.7, d7 = 3.7, and the sheet resistance values of the resistance layer and the reflection layer are 193Ω □ and 5.0, respectively.
It is Ω □.

FIG. 27 is a graph showing the return loss of the radio wave in the 5.8 GHz band with respect to the incident angle of the radio wave in the second embodiment. The return loss of the circular polarized wave A, the TM wave B, and the TE wave C is shown in FIG. Has a peak near an incident angle of 40 to 50 degrees due to the use of two types of dielectric materials having different dielectric constants. The circularly polarized wave A has a return loss of 20 dB or more in an incident angle range of 0 to 80 degrees with respect to the electromagnetic wave absorber, and a favorable electromagnetic wave absorption characteristic is obtained as a wide incident angle electromagnetic wave absorber. Also, regarding the TM wave B and the TE wave C, the reflection attenuation amount is 20 dB or more in the range of 0 degrees or more and 55 degrees or less, and the reflection attenuation amount is 15 dB or more in the range of the incident angle of 0 degrees or more and 60 degrees or less. The attenuation factor is obtained, and good electromagnetic wave absorption characteristics are obtained.

[0082]

According to the unnecessary radio wave suppression method of the present invention, a transparent radio wave absorber is attached to a road incidental facility, or a main part of these road incidental facilities is formed from a transparent radio wave absorber, which is unnecessary. By preventing the reflection and transmission of various radio waves, the function according to the purpose installed can be achieved, and since the radio wave absorber is transparent, the radio waves can be shielded without blocking the field of view or light rays. It is possible to effectively suppress unnecessary radio waves during communication or sensing used.

Further, in the transparent electromagnetic wave absorber, the second dielectric is formed by laminating a plurality of dielectrics having different dielectric constants, so that the thickness is adjusted according to the difference in the dielectric constants of the respective dielectrics.
By changing the incident angle to the resistive film and the phase of the radio wave, the characteristics of radio wave absorption with respect to the incident angle can be adjusted to 5.8G.
For circularly polarized radio waves in the Hz band, the return loss is 2 when the angle of incidence on the radio wave absorber is 0 to 80 degrees.
It is set to 0 dB or more and is provided with a well-balanced electromagnetic wave absorption characteristic from a low incident angle to a high incident angle, and it is possible to more reliably prevent misidentification during communication or sensing. The second dielectric includes a second first dielectric arranged on the radio wave arrival side of the resistance film and a second second dielectric arranged on the radio wave arrival side of the second first dielectric. The second second dielectric is composed of at least two dielectrics, and the second dielectric has a higher dielectric constant than the second first dielectric, so that the characteristic of the radio wave absorption with respect to the incident angle can be easily adjusted. Further, the second first dielectric may consist of air.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing how radio waves are reflected by a road auxiliary equipment.

FIG. 2 is an explanatory diagram showing how radio waves are reflected by road-related equipment.

FIG. 3 is an explanatory diagram showing a situation in which unnecessary radio waves are generated in road auxiliary equipment.

FIG. 4 is an explanatory diagram showing a situation in which unnecessary radio waves are generated in road auxiliary equipment.

FIG. 5 is an explanatory diagram showing an example of a flow of radio waves bidirectionally communicated between road vehicles in a road vehicle communication zone for AHS to which the embodiment of the present invention is applied.

FIG. 6 is a cross-sectional view showing a configuration of a radio wave absorber showing an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing another embodiment of a radio wave absorber according to the present invention.

FIG. 8 is an explanatory diagram in which a radio wave absorber is attached to a sound insulation wall to which one embodiment of the present invention is applied.

FIG. 9 is an explanatory diagram in which a radio wave absorber is attached to a sound insulation wall to which an embodiment of the present invention is applied.

10 is a cross-sectional view of the sound insulation wall shown in FIG.

FIG. 11 is an explanatory diagram showing another embodiment in which a radio wave absorber is attached to a sound insulation wall to which the present invention is applied.

FIG. 12 is an explanatory diagram showing an embodiment in the vicinity of a toll gate according to the present invention.

FIG. 13 is an explanatory diagram showing one embodiment of the periphery of the ETC according to the present invention.

FIG. 14 is an explanatory diagram showing another form of road incidental equipment having radio wave absorption performance.

FIG. 15 is an explanatory diagram showing another form of road incidental equipment having radio wave absorption performance.

FIG. 16 is an explanatory diagram showing another form of road incidental equipment having radio wave absorption performance.

FIG. 17 is an explanatory diagram showing another form of road incidental equipment having radio wave absorption performance.

FIG. 18 is an explanatory diagram showing another form of road incidental equipment having radio wave absorption performance.

FIG. 19 is an explanatory diagram showing another form of road incidental equipment having radio wave absorption performance.

FIG. 20 is a cross-sectional view showing an example of implementation of a transparent electromagnetic wave absorber according to the present invention.

FIG. 21 is a graph showing the radio wave absorption characteristics of the transparent radio wave absorber shown in the example.

[Explanation of symbols]

1 road 11 outer wall 12 medians 2 Road incidental equipment 21 sound insulation wall 22 Guard fence 2A partition wall 2Aa, 2Ab, 2Ac Partition wall 2A1 basics 2A2 prop 2B lighting cover 2C toll gate window 2D road sign 2E tunnel interior plate 2F Girder back cosmetic plate 2G wall balustrade 2H guardrail 2J Road sign device 3 Roadside communication equipment 31 props 32 beams 33 gates 4 vehicles 4C passenger car 4T truck 4M mixer truck 41 Onboard communication device 5 Radio wave absorber 51 Resistance layer 52 reflective layer 53 Second dielectric 531, 532, 533 Dielectric 54 First Dielectric 55 Back protection 6 bolts 7 islands 8 toll gates 81 Tollgate roof 82 prop a radio wave a1 unnecessary radio wave a2 Indirect radio waves

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshito Hirai             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. (72) Inventor Koji Takizawa             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. (72) Inventor Fukuji Miyazato             2-4-4 Nishitenma, Kita-ku, Osaka-shi, Osaka             Sekisui Jushi Co., Ltd. (72) Inventor Satoshi Fujita             731-1 Tanida, Ryō-cho, Gamo-gun, Shiga Prefecture               Sekisui Jushi Co., Ltd. (72) Inventor Toru Hagiwara             731-1 Tanida, Ryō-cho, Gamo-gun, Shiga Prefecture               Sekisui Jushi Co., Ltd. (72) Inventor Kenichi Kimura             731-1 Tanida, Ryō-cho, Gamo-gun, Shiga Prefecture               Sekisui Jushi Co., Ltd. (72) Inventor Ichiro Fukuro             731-1 Tanida, Ryō-cho, Gamo-gun, Shiga Prefecture               Sekisui Jushi Co., Ltd. F-term (reference) 2D001 AA01 BA01 CA01 CB01 DA04                 5E321 AA41 AA50 BB23 BB25 BB60                       GG11 GH01                 5J020 EA03 EA04 EA05 EA07 EA10

Claims (28)

[Claims] 1. In order to suppress unnecessary radio waves generated by surrounding road auxiliary equipment at the time of communication or sensing using radio waves, a transparent electric wave absorber is attached to the road auxiliary equipment, or The main part is formed of a transparent electromagnetic wave absorber, and the transparent electromagnetic wave absorber has a transparent resistance film arranged in the direction of arrival of the electromagnetic wave, and has a thickness of about λg / 4 on its back surface.
A transparent first dielectric (where λg represents the wavelength of the radio wave in the dielectric) is arranged, and a radio wave reflector that transmits light is further arranged on the back surface of the dielectric, and the radio wave of the resistance film is further arranged. A transparent second dielectric is arranged on the arrival side, and the second dielectric is
It is formed by laminating a plurality of dielectrics having different permittivities, and has a return loss of circularly polarized waves in the 5.8 GHz band within a range of an incident angle of 0 to 80 degrees with respect to the electromagnetic wave absorber. A method for suppressing unnecessary radio waves, which is 20 dB or more. 2. A plurality of transparent dielectrics having different dielectric constants,
A second first dielectric body arranged on the radio wave arrival side of the resistance film and a second first dielectric body arranged on the radio wave arrival side of the second first dielectric body.
Of at least two of the two dielectrics of
2. The unnecessary radio wave suppression method according to claim 1, wherein the second dielectric has a higher dielectric constant than the second first dielectric. 3. The unnecessary radio wave suppression method according to claim 2, wherein the second one dielectric is made of air. 4. The resistance film is formed by ion plating a metal, a metal oxide, a metal nitride or a mixture thereof.
The unnecessary radio wave suppression method according to any one of claims 1 to 3, which is a transparent film formed by vapor deposition, sputtering, coating, or the like. 5. A metal, a metal oxide, and a metal nitride are silver,
The unnecessary radio wave suppressing method according to claim 4, wherein the unnecessary radio wave is at least one selected from the group consisting of ITO (indium oxide / tin oxide), tin oxide, zinc oxide, and titanium nitride. 6. The unnecessary material according to claim 1, wherein the transparent dielectric material is at least one material selected from the group consisting of air, glass, and transparent organic polymers. Radio suppression method. 7. The unnecessary radio wave suppressing method according to claim 1, wherein the radio wave reflector is a metal wire grating and / or a transparent metal thin film. 8. The transparent metal thin film is made of metal, metal oxide,
8. The unnecessary radio wave suppression method according to claim 7, which is a transparent film formed by ion plating, vapor deposition, sputtering, coating or the like of a metal nitride or a mixture thereof. 9. The metal, the metal oxide and the metal nitride are silver,
9. The unnecessary radio wave suppression method according to claim 8, wherein the method is at least one selected from the group consisting of ITO (indium oxide / tin oxide), tin oxide, zinc oxide, and titanium nitride. 10. The transparent wave absorber according to claim 1, wherein at least one of the constituent layers is bonded by using a transparent adhesive synthetic resin. The unnecessary radio wave suppression method described in. 11. The transparent adhesive synthetic resin is EVA.
11. At least one selected from the group consisting of (ethylene vinyl acetate copolymer), PVB (polyvinyl butyral), modified polyethylene, modified polypropylene, epoxy-based adhesive, and urethane-based adhesive. The unnecessary radio wave suppression method described. 12. The communication using radio waves is road-to-vehicle communication in which a roadside communication facility installed on a road and a vehicle-mounted communication device mounted on a vehicle perform wireless communication. The unnecessary radio wave suppression method according to any one of 1. 13. The road-to-vehicle communication is communication performed in a driving support road system.
The unnecessary radio wave suppression method described in 2. 14. The unnecessary radio wave suppression method according to claim 12, wherein the road-to-vehicle communication is short range communication. 15. The communication using radio waves is an inter-vehicle communication in which a plurality of vehicles equipped with an in-vehicle communication device perform wireless communication by the in-vehicle communication device.
11. The unnecessary radio wave suppression method according to any one of 1 to 11. 16. The vehicle-to-vehicle communication is communication performed in a driving support road system.
5. The unnecessary radio wave suppression method described in 5. 17. Sensing using radio waves is performed by a vehicle equipped with an in-vehicle receiving device, by receiving radio waves transmitted from a transmitting device built in or attached to a road auxiliary equipment. The method of suppressing unnecessary radio waves according to any one of claims 1 to 11. 18. The transparent radio wave absorber suppresses unnecessary radio waves generated by reflection and / or transmission of radio waves to peripheral road auxiliary equipment that performs communication or sensing using radio waves. The unnecessary radio wave suppression method according to any one of claims 1 to 17, wherein 19. The transparent wave absorber has a frequency of 5.
19. The unnecessary radio wave suppression method according to claim 18, wherein transmission of radio waves in the 8 GHz band is suppressed. 20. The unnecessary radio wave suppressing method according to claim 1, wherein the transparent radio wave absorber has a coating for preventing water droplets from adhering to an outer surface thereof. 21. The road auxiliary equipment is characterized in that a main component is at least one transparent material selected from the group consisting of polycarbonate resin, acrylic resin, polyacrylonitrile resin, polyvinyl chloride resin, and glass. The unnecessary radio wave suppression method according to any one of claims 1 to 20. 22. The road auxiliary equipment includes a soundproof wall, a tunnel interior plate, a girder back face decorative plate, a viaduct leg decorative plate, a road sign, a wall balustrade, a toll booth, a toll booth window, a guardrail,
The unnecessary radio wave suppressing method according to any one of claims 1 to 21, wherein the unnecessary radio wave suppressing method is at least one selected from the group consisting of a fence, a line of sight indicator, a point marker, an emergency telephone, a traffic signal, and a footbridge. 23. The road auxiliary equipment is a partition wall which is installed at a peripheral edge of a lane having a communication area by radio waves and which prevents unnecessary transmission and / or reflection of radio waves from the communication area. 22. The unnecessary radio wave suppressing method according to claim 1. 24. The unnecessary radio wave suppression method according to claim 23, wherein the road incidental equipment is installed at the edge of the lane of the automatic toll collection system. 25. The road auxiliary equipment is a partition wall between lanes in the same direction or between lanes facing each other, and the partition wall is installed in a toll gate and / or between lanes around the toll gate. 25. The unnecessary radio wave suppression method according to claim 23 or 24. 26. The road incidental equipment is an illuminating lamp, wherein the illuminating lamp cover is formed of a transparent radio wave absorber, and unnecessary radio waves are transmitted into the illuminating lamp cover and / or the illuminating lamp cover. 22. The unnecessary radio wave suppression method according to claim 1, wherein reflection from inside is prevented. 27. The unnecessary radio wave according to claim 26, wherein the road auxiliary equipment is an illumination light, and the illumination light is installed in and / or around the tollgate. Suppression method. 28. A road auxiliary equipment to which a radio wave absorber is attached or a main part is composed of the radio wave absorber in order to suppress unnecessary reflection of the radio wave at the time of communication or sensing using the radio wave. The absorber has a transparent resistance film arranged in the direction of arrival of radio waves, and a transparent first dielectric having a thickness of approximately λg / 4 (where λg represents the wavelength of the radio waves in the dielectric) on the back surface of the absorber. Further, a radio wave reflector that transmits light is arranged on the back surface of the dielectric body, and a transparent second dielectric body is further arranged on the radio wave incoming side of the resistance film, and the second dielectric body has a different dielectric constant. Formed by stacking multiple dielectrics, and 5.8G
For circularly polarized radio waves in the Hz band, the return loss is 20 dB or more within the range of the incident angle of 0 to 80 degrees to the radio wave absorber, and the road incidental equipment is a soundproof wall or a tunnel. Interior board, girder back decorative board, viaduct leg decorative board, road sign, wall balustrade, toll gate roof, toll gate window, guardrail, fence, line of sight indicator, point mark, emergency telephone, traffic signal, pedestrian bridge, communication area At least one selected from the group consisting of a partition wall installed on the edge of a lane and an illumination lamp, and a road accessory.